Dimensions and Design of swimming pool fences and balcony - ANEC

fast body changes or in early stages of motor
acquisitions. It becomes clear that risk behaviour
must be individually defined, and it relates to
subjects’ characteristics as well as environmental
specific demands. According to the
ecological approach the individual guides his
activity by perceiving affordances, so he must
be capable of perceiving the relationship
between environmental properties and the
properties of his own action system.
2.3.6 Perceiving action limits
As we previously mentioned babies have
constrained action possibilities. For instance,
they are moved by others before they can
move by their own means, but they have full
access to visual and auditory information.
The information that they pick up from their
environment supports the extraction of
invariants, i.e., the common things that are
perceived in the presence of a repeated
event. Individual experience, of course,
generates the detection of what can be done
with an object or within a specific situation
(Gibson, 1969).
During development children learn how to cope
with the existing affordances, such as the ability
of passing over surfaces due to their properties
and negotiable paths, as their own body’s
proportions, strength and capacity for balance
are changing (Gibson & Pick, 2000).
In the process of perceiving affordances children
often try to gain experience by pushing the limits
of their capabilities. Inefficient or dangerous
behaviours usually occur when people,
especially children are close to their action
boundaries (Barreiros & Silva, 1995). When a
wall is too high it inhibits jumping; when it is
low enough, jumping is promoted; but in the
boundary zone there is an increased uncertainty
that might lead to unsafe behaviour. The precise
delimitation of affordances in this unsafe
boundary area requires specific experience on
specific environmental constraints. At this point
a new paradox emerges: children may
experience dangerous behaviour because they
have no experience but the acquisition of
experience seems to be a dangerous process.
Many studies have shown that falling accidents
are more frequent between 2 and 6 years of age,
and this roughly corresponds to a period of
experimentation and development of the
perception of action limits. Balconies, windows,
and stairs represent nearly 50 % of fall related
injuries, while falling from trees, play
equipments and other “educational” structures
represent less than 10 % of related episodes
(Kim, Wang, Griffith, Summers & Levy, 2000).
When the opportunity for perceiving
environmental affordances is restricted, and the
competence for the detection of action limits is
poor, accidents seem to occur mainly in nonplay
context.
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Faculdade de Motricidade Humana
Universidade Técnica de Lisboa